This invention relates to semiconductor memory devices, memory chips, memory modules, and the handling of defective memory components.
Due to the yield limitation of semiconductor fabrication process, a semiconductor memory wafer usually contains defective memory devices. These defective memory devices are declared as unusable because the defects within the device are beyond the repairing capability of the device fabrication process.
We may categorize the types of defective memory devices by the defective data bit positions. For a memory device with eight data bits, there are 255 types of defective memory devices. The large number of defective memory types further complicates the issue regarding to the handling, sorting, and packaging of these memory devices.